Motor Grader Speed Sensor – Signal, Gap and Connector Guide
A speed sensor may monitor a transmission shaft, wheel-related component or another rotating target. Sensors that share a similar threaded body can still differ in electrical principle, output, pin assignment, probe length and required air gap.
Identify the complete sensing arrangement
| Sensor evidence | Body code, manufacturer marks and wire or pin count |
| Mechanical fit | Thread or flange, probe length, shoulder, seal and connector orientation |
| Electrical match | Supply requirement, output type, pin assignment and expected signal |
| Target relationship | Tooth or trigger pattern, air gap and installation position |
Diagnosis before parts replacement
Inspect the connector for oil, water, bent pins and poor retention. Check the harness for abrasion near moving or hot components. Look through the sensor opening, where safe, for damaged teeth or debris on the target. A magnetic probe may collect fine metal particles that weaken the signal without an internal sensor failure.
Air gap and signal quality
Use the machine service specification for installation depth or air gap. Too large a gap can reduce signal strength; contact with the rotating target can damage both parts. If testing the output, use the procedure and measuring equipment appropriate to the sensor type—do not assume every unit produces the same waveform.
Related drivetrain references
For a rotating component that can affect speed-signal stability, see the intermediate shaft inspection guide. For dashboard indication checks, compare the operator panel page.
FAQ
Can a two-wire and three-wire sensor be interchanged?
Not by appearance alone. Their supply and output principles may differ.
Will a new sensor fix an intermittent speed reading?
Not necessarily. Connector condition, wiring, target damage, air gap and controller input must be checked.
Why is probe length important?
It controls the relationship to the rotating target; an incorrect length can cause a weak signal or physical contact.
Can resistance alone prove a sensor is good?
No universal resistance test applies to every sensor type. Follow the correct circuit procedure.
Compatibility note: Match the code, signal type, pinout, mounting, probe length and target arrangement before ordering.
